Heretofore, services referred to as “chat” have been offered for the purpose of real-time text communication using PC (Personal Computer) terminals, mobile terminals, and other information processing devices. Multi-functional mobile terminals called smartphones have been rapidly growing in popularity since 2010. Numerous chat services predicated on being used with mobile terminals have been offered, and their user bases continue to expand. Due to the increased popularity of such services, it has been expected that new services and functionalities will appear and allow for shared communities to be formed even among friends who may not be previously acquainted.
For example, as disclosed in Patent Document 1, a user who has joined an SNS (Social Networking Service) uploads an image and tags it with the identification information of the users associated with the image. The tagged image is made public, to a certain extent, including its association with the user, thereby promoting the creation of a new community.